This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 58 |
| 5 | 321 |
| 6 | 1963 |
| 7 | 13053 |
| 8 | 92946 |
| 9 | 702864 |
| 10 | 5599204 |
| 11 | 46746501 |
| 12 | 407019340 |
| 13 | 3682922657 |
| 14 | 34519445611 |
| 15 | 334288656446 |
| 16 | 3336972646500 |
| 17 | 34270606413428 |
| 18 | 361466138304372 |
| 19 | 3909661505975148 |
| 20 | 43305438098350844 |
| 21 | 490632571238216052 |